features: Feature Extraction for Discretely-Sampled Functional Data

Discretely-sampled function is first smoothed. Features
of the smoothed function are then extracted. Some of the key
features include mean value, first and second derivatives,
critical points (i.e. local maxima and minima), curvature of
cunction at critical points, wiggliness of the function, noise
in data, and outliers in data.